Magnetospheric jets on Earth are plasma formations that have higher dynamic pressure around the plasma and can cause energy-transferring waves in such environments. Such jets also exist beyond Earth in the Martian magnetosphere, as Herbert Gunnell and a research team from Umeå University’s Department of Physics and the Swedish Institute for Space Physics in Sweden have observed using the MAVEN spacecraft database. Team results are now released Science Advances.

The extraterrestrial counterpart of this terrestrial phenomenon is relatively different on Mars due to the smaller main shock wave and is associated with increased magnetic field fluctuations like jets in the Solar System affecting the astrophysical plasma. In this paper, the research team included analysis of a single spacecraft database to confirm the presence of jets in Mars’ magnetosphere.

The formation and propagation mechanism of the Earth’s magnetosphere: Implications for Mars

Astrophysicists initially only assumed the existence of magnetospheric jets on Earth. However, the shock phenomenon is ubiquitous in astrophysics, as all planets have major shocks, as with some comets. Data obtained by the MAVEN spacecraft in this study provided a clear picture of the presence of jets in Mars’ magnetosphere.

When the solar wind collides with the Earth’s magnetic field, the transition from supersonic to subsonic flow creates the main shock wave. The delayed solar wind can form a magneto sheath, a compressed region of heated plasma. Magnetosheath currents result from the dynamic representation of plasma pressure due to increased density and/or velocity on Earth. Initially, astrophysicists studied the motion of jets in magnetic fields in the laboratory, using a vacuum with a background plasma to create plasmoids. Researchers first reported this phenomenon on Earth in the late 1990s, and it has now sparked a significant amount of research.

Jets can generate waves in the magnetosphere to cause surface waves and Alfvén wave radiation detected by ground-based magnetometers. This concept is also related to the phenomenon known as throat auroras. Most mechanisms of mainshock formation and magnetospheric creation suggest interaction of solar winds with mainshock eddies, relatively short-lived large-amplitude magnetic structures (SLAMS) or hot flow anomalies, and bowshock remodelling. Jets are an integral part of reducing the main shock scale in the magnetosphere and transferring solar wind energy to wave energy through the plasma medium.

Analysis of MAVEN spacecraft data

Gunnell and colleagues presented three examples of jets observed by the MAVEN spacecraft on January 28 and 29, 2017 and June 10, 2020. During the first scale of observations, the team projected the spacecraft’s position on the major planes of Mars. solar orbital coordinate system. In the study, they presented the result schematically with dashed and straight lines to show the bow shock absorber model. During subsequent analyses, the spacecraft did not enter the solar wind; therefore, the parameters of the second time frame were estimated from measurements in the magnetosphere.

The ion spectrum from the database showed many populations of protons and alpha particles. Alpha particles took longer to thermalize after mainshock, compared to protons, due to their larger radius of rotation. The team also examined the comparative proximity of the magnetosphere jets to the planet Mars in two time periods in 2017 and 2020, showing that the phenomenon was closer to the planet in an earlier time period than the last time period detected and documented by the MAVEN spacecraft.

The evolution of the bow shot

By June 10, 2020, the team observed that the jet magneto sheath was emerging downstream and at a higher altitude. They observed two pulses of increased dynamic pressure, and the greater distance from the mainshock caused alpha particles and protons to mix rather than appear as separate populations. The increased dynamic pressure of the scenario was due to increased intensity, where the magnetic field fluctuations showed a higher amplitude within the jets.

Astrophysicists continued to observe the main shock and the interplanetary magnetic field. A single spacecraft study provided a simple estimate of jet size. Gunnell and colleagues compared the size of the jet with the scale of the magnetosphere to understand the shape and origin of the jet. For example, they recorded a jet size in the 4,000-18,000 km range in the ion velocity direction, well beyond the distance traveled by the observatory’s spacecraft.

In this way, Herbert Gunnell and colleagues demonstrated how the ubiquitous and geo-effectual phenomenon of magneto-sheath jets on Earth can generate waves and transfer energy within the magneto-sheath. Although such phenomena exist at a different scale and nature in the Martian magnetosphere outside of Earth’s atmosphere, they play the same role in both planetary environments.

The researchers suggest that in the future, larger statistical studies will be used to measure the geo-activity of magneto-sheath jets on Mars, which are suitable for various solar wind conditions to encompass all regions of space around the planet. Source